Conventionally, known is virtualization technology of arranging one or more virtual machines (hereinafter referred to as the “virtual guest(s)”) on a server apparatus having a virtualization function (hereinafter referred to as the “virtual host”), and dynamically assigning a physical resource (hereinafter referred to as the “resource”) to each of the one or more virtual guests that were arranged.
Note that the term “virtual guest” refers to virtualization software that runs on a hypervisor of the virtual host. Moreover, the term “resource” refers to physical resources such as a CPU (Central Processing Unit), a memory, a disk adapter and a network adapter configuring the virtual host, and a storage capacity of the storage apparatus that provides a storage area to the virtual host.
Moreover, in recent years, known is virtualization technology of migrating (relocating) a part of one or more virtual guests arranged on a virtual host to another virtual host with a lower processing load. This virtualization technology related to the migration of virtual guests is disclosed, for example, in PTL 1 indicated below.
PTL 1 discloses a virtual machine management apparatus capable of ensuring the processing performance of a plurality of virtual guests while realizing cost reduction, in a system including a plurality of virtual hosts on which each of the virtual guests is running, by appropriately arranging the virtual guests in the virtual hosts.
Specifically, disclosed is technology of collecting the usage of resources to be used by the virtual guest and the amount reserved (margin) which is expected to be additionally required, combining the collected usage and margin of the resources, and calculating the combined amount of resources as the amount of resources that is required by the virtual guest. Note that the margin which is expected to be additionally required is calculated based on the amount of resources that was used when the processing of that virtual guest was at its peak.
Subsequently, when migrating the migration-target virtual guest to another virtual host with a lower processing load, the virtual host on which a virtual guest, having a margin that is similar to that of the migration-target virtual guest, is running, is selected as the destination virtual host.
Since virtual guests with similar margins can be aggregated and arranged as a result of selecting the destination virtual host as described above, if a margin in an amount similar to that of the margin of the aggregated and arranged virtual guests is reserved in the virtual host as the fluctuation portion of the future throughput, it is possible to basically deal with the increase of throughput without having to reserve extra margin.